长江三角洲地区降水集中度和集中期的时空变化特征
首发时间:2015-01-15
摘要:基于长江三角洲地区33个台站1960-2011年逐日降水资料和同期NCEP/NCAR逐月再分析资料,采用趋势分析、小波分析、相关分析等方法,对长江三角洲地区雨季降水集中度(PCD)和集中期(PCP)的时空变化特征进行了研究。结果表明,长江三角洲地区雨季降水集中度平均为0.27,集中期平均为36.5侯;在空间上PCD和PCP都表现为由南向北逐渐增加,与雨季降水量分布特征相反;在时间上雨季降水量、PCD和PCP都表现出一致的增加趋势,尤其是中东部地区增加趋势更为明显;PCD、PCP和雨季降水量的年际和年代际变化存在准2a、3-4a、8a和16a左右的周期振荡。长江三角洲地区的雨季降水量与集中度和集中期存在较好的正相关,多水年和少水年降水集中度的空间分布明显不同。蒙古高压偏强、副热带高压西伸是长三角地区降水较集中的大气环流背景;PCD偏高年,长三角地区上空环流场呈气旋性辐合,水汽输送充沛,而PCD偏低年环流场辐散增强,水汽输送较少。
关键词: 长三角地区 降水集中度 降水集中期 时空分布 大气环流
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Temporal and Spatial Variation Characteristics of Precipitation Concentration Degree and Precipitation Concentration Period in the Yangtze River Delta
Abstract:Based on the daily precipitation data from 33 weather stations in the Yangtze River Delta from 1960 to 2011 and the grid data of NCEP/NCAR, and trend analysis, wavelet analysis and correlation analysis were also employed, this article aims to analyze the characteristics of spatial and temporal distributions and variations of the precipitation concentration degree (PCD) and concentrated period (PCP) in the Yangtze River Delta over rainy season. The result shows that the average PCD is 0.27 and the average PCP is 36.5 pentads. In the spatial distribution of PCD and PCP gradually increased performance from south to north, and in contrast with the distribution of precipitation during the rainy season. In the Temporal of precipitation, PCD and PCP display increasing trend, especially in the eastern region the trend is more evident. The Interannual and decadal variation of PCD and PCP have the quasi-biennial, 3 to 4 years, 8 years and 16 years period oscillation with precipitation. There is a positive relationship between PCD, PCP and precipitation over the Yangtze River Delta in rainy season, it is found that the spatial distribution of PCD in the year with more precipitation is obvious different from the less one. In the higher PCD years, the atmospheric circulation background shows that the anomaly of 500hPa geo-potential height field is positive in Mongolian Plateau and the subtropical high over western Pacific westwards. There is obvious cyclonic convergence and abundant moisture transport near the Yangtze River Delta in the higher PCD years. The result will be opposite in the lower PCD years.
Keywords: Yangtze River Delta Precipitation concentration degree Precipitation concentration period Spatial and temporal distributions atmospheric circulation
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No.4627067103031514****
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